migrate: to gotl

[CodeShellDev]

Summary

We are migrating from managing the utils locally, to using them remotely with gotl.
Many utils should definetly belong into a separate repo for easier access.
templating.go was pretty specific to SSA, so we might move some funcs from gotl back into here,
if we ever feel the need to change funcs in the templating module.

Changes

• removed most of utils/
• added imports for gotl/pkg

=> -0.1MB (according to docker images)

Checklist

• PR tested
• Docs updated (if applicable)